This invention relates to a dryer, and more particularly to a dryer wherein a vacuum or subatmospheric pressure is established within the dryer, which, together with the application of heat, produces drying of material handled. The dryer is particularly suited for the drying of veneer or similar sheet material which can be prepared as a layered stack within the dryer.
Because the dryer of the invention utilizes a vacuum, moisture within the material being processed vaporizes at a lower temperature than in conventional type dryers. As a consequence, for a given dryer temperature, drying may be performed more rapidly than with other types of dryers. With a lower temperature used in drying, resinous materials which vaporize at the higher temperatures typifying conventional dryers tend not to be vaporized and expelled into the atmosphere. This substantially minimizes pollution problems that characterize conventional dryers.
In a dryer constructed pursuant to the invention, a pair of relatively movable, opposed platens are brought together, and under the action of vacuum press against opposite sides of the load handled. These walls are supported by the load, and there is an absence in the dryer of substantial containment walls that must be adequately braced to withstand the atmospheric pressure which is present on the outside of the dryer. The dryer features a novel construction for sealing one platen against the other, whereby a vacuum may be established within the dryer. The invention further embraces, in one modification thereof, the provision of a conveyor whereby material may be easily transported into and out of the dryer.
A general object of the invention, therefore, is to provide an improved dryer for heating material, such as wood veneer, which relies on the application of heat and also the establishment of a vacuum to produce the drying action.
Another object is to provide such a dryer which has a minimal extent of containment walls functioning to define the limits of a vacuum chamber within the dryer.
Another object is to provide a dryer with improved means for sealing together relatively movable sections in the dryer.
A dryer constructed according to the invention readily adapts itself to the handling of loads of different thickness. A dryer pursuant to the invention may be relatively simply constructed, and at low cost.